The mechanisms of electrophoretic deposition (EPD) are discussed and their shortcomings identified. The kinetics of the processes involved are analyzed for constant‐current and constant‐voltage conditions. A method of determining the Hamaker constant of suspended particles is developed by modeling the relationship between the particle inter‐action energy and the suspension stability. A three‐probe dc technique is used to map the voltage profile around the depositing electrode, and the results are used to explain discrepancies between the calculated and experimentally observed voltage drops during deposition. A mechanism of deposition is proposed based on DLVO theory and particle double‐layer distortion/thinning on application of a dc field to the suspension. Kinetic equations are developed for constant‐current and constant‐voltage EPD using mass balance conditions; these are verified by experiments. After the phenomenon is introduced and discussed, a critique of the application of EPD to the synthesis of ceramic shapes and coatings is given.

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A tubular anode‐supported “micro‐solid oxide fuel cell” (μSOFC) has been developed for producing high volumetric power density (VPD) SOFC systems featuring rapid turn on/off capability. An electrophoretic deposition (EPD)‐based, facile manufacturing process is being refined to produce the anode support, anode functional and electrolyte layers of a single cell. μSOFCs (diameter <5 mm) have two main potential advantages, a substantial increase in the electrolyte surface area per unit volume of a stack and also rapid start‐up. As fuel cell power is directly proportional to the active electrolyte surface area, a μSOFC stack can substantially increase the VPD of an SOFC device. A decrease in tube diameter allows for a reduction in wall thickness without any degradation of a cell's mechanical properties. Owing to its thin wall, a μSOFC has an extremely high thermal shock resistance and low thermal mass. These two characteristics are fundamental in reducing start‐up and turn‐off time for the SOFC stack. Traditionally, SOFC has not been considered for portable applications due to its high thermal mass and low thermal shock resistance (start‐up time in hours), but with μSOFCs' potential for rapid start‐up, new possibilities for portable and transportable applications open up.

widespread skepticism concerning the importance of electroAlumina (Al 2 O 3 ) powders have been dispersed in ethanol statics in organic media" and warned against its negligence. (EtOH) solutions of different acidity. In aqueous media, If a certain degree of electrolyte dissociation can be obtained acidity is defined by pH. This definition can be extended to in a medium of low dielectric constant, and a high surface nonaqueous media using ion-transfer functions. The electripotential be created, significant repulsive forces should be poscal charge on the particle surfaces has been found to be sible. This is feasible in polar organic media, such as the lower acidity dependent. The electrostatic stability of Al 2 O 3 -alcohols, with moderate dielectric constant. EtOH suspensions has been evaluated via electrophoresisThe Derjaguin-Landau-Verwey-Overbeek (DLVO) theory 9 and turbidity. An electrostatic stabilization mechanism is makes it possible to quantify the electrostatic stability of lyoproposed and analyzed via Derjaguin-Landau-Verweyphobic colloids. Although the theory was developed for aqueOverbeek (DLVO) theory.ous systems, it also is applicable to nonaqueous media of low dielectric constant. As the double-layer potential decays slowly I. Introduction in nonaqueous media, the particle surface potential and zeta potential () (the potential at the shear plane) are approximately T HE fabrication of ceramic materials involves powder proequal. 3-5 cessing, shaping, and firing. The reliability of ceramic prodSolid oxide powders in aqueous suspension possess a ucts is dependent on the uniformity of their microstructure.pH-dependent surface electrical charge. Recently, Kosmulski The latter can be accomplished most effectively by processing and Matijevic 10 investigated the zeta potential of silica in a colloidal suspensions. Reproducible and optimized colloidal water-alcohol mixture and demonstrated the effect of pH on processing is dependent on control of the stability of colloidal the zeta potential. suspensions.The present paper is concerned with correlating the pH scales The search for tough structural ceramics has led to the for different solvents and investigating the effect of pH on the development of laminar ceramic composites. Electrophoretic surface charge on Al 2 O 3 particles in ethanolic suspensions. deposition is a powerful technique for the synthesis of laminar Dispersion stability is evaluated by electrophoresis, and turmicrocomposites with a minimum layer thickness of ϳ2 m bidity and particle interaction are analyzed via interactionand an interfacial smoothness of submicrometer scale. 1 energy calculations using the DLVO theory. The traditional medium for ceramic powder dispersion is water. However, electrophoretic deposition from aqueous suspensions has the disadvantage of electrolysis at low potentials.